Stabilized dune ridges in northern Saskatchewan

Abstract

Stabilized dune ridges occurring in northern Saskatchewan have previously been identified as variedly as "ice-crack moraines" and longitudinal dunes. Investigations of their morphological, structural, and sedimentary attributes reveal that they are, indeed, of eolian origin, but they form a particular group within the parabolic dune association, namely, the "Cree Lake type dune ridges." The ridges occur in association with other types of parabolic dunes and other eolian features, such as loess and wind-abraded glacial blocks and bedrock outcrops. The dunes and the associated eolian features were all formed by southeasterly paleowinds of uniform direction. The dune ridges developed from primary parabolic dunes of simple and composite types through the process of dune elongation. At the same time, exposed rock surfaces were abraded by the wind and loess was deposited downwind from the developing dune fields. The southeasterly direction of the paleowinds, which is almost directly opposite to the direction of the present-day winds affecting dunes in the Lake Athabasca area, was due to adiabatic air masses coming off the ice sheet from the east and affected eolian activity in quite a large region in northern Saskatchewan and Alberta. The somewhat cool and sufficiently dry adiabatic winds checked the vegetation on the dunes and in the areas around them. The development of the dune ridges came to an end when a sudden climatic change evoked the rapid stabilization of the dunes by vegetation but not before most of the ridges became partly deformed by southwesterly crosswinds resulting from the same climatic change. The period of eolian activity is estimated from the age of the local ice frontal positions to have been between 10 000 and 8800 years BP. Only one other region is known from North America, namely, the St. Lawrence Lowland in the east, where analogous eolian environment prevailed in the zone peripheral to the continental ice sheet and produced comparable eolian features.

Late glacial ? early holocene palaeosalinity in Alberta, Canada ? climate implications

“…Relatively dry, warm winds from the southeast would have affected the Goldeye Lake region. Such winds have been implicated in sand-dune formation in northeastern Saskatchewan (David, 1981). Further evidence of aridity at this time is provided by Vance (1986) from a lake record from northeastern Alberta.…”

Morphology and Formation of an Holocene Coastal Dune Field, Bruce Peninsula, Ontario

“…Those of the windward * slope ranged from 15° to 34°, with a mean of 26° and a mode of 25°. In several profiles the windward slope is actually steeper than the leeward slope, with the steeper slopes usually associated with greater overall dune height, as recorded for I dunes in Saskatchewan by David (1981 ). Because both sides are steep, the dune ridge is quite narrow, ranging from 40-J 70 m at measured sections.…”

The pattern and style of deglaciation at the Late Wisconsinan Laurentide and Cordilleran ice sheet limits in northeastern British Columbia

“…2C-2E). Over this time frame, unglaciated terrain and unconsolidated deposits exposed by ice retreat and lake drainage were reworked by katabatic winds to form dune fields and widespread loess deposits supporting tundra ecosystems (David 1981;Begét 2001;Porter 2001;Wolfe et al 2004;Dyke 2005).…”

“…Dunes stabilized around 13.0 ± 0.5 ka with the establishment of tundra vegetation on deglaciated terrain, and as the climate became increasingly influenced by the Pacific air mass (cf. David 1981;Wolfe et al 2004;Hickin et al 2015).…”